Asphalt shingles were a popular choice for American homes in the housing boom that followed World War II. The original substrate was organic felt made from rags, waste paper and wood chips. Fiberglass was seen as a superior reinforcement because it would not absorb moisture, so by the mid-1950s a fiberglass-reinforced asphalt shingle was developed and introduced in the U.S. Despite the best efforts of the fiberglass industry to get the shingle industry to adopt the improved reinforcement, which could enable shingles to achieve a Class A fire rating, shingle manufactures opted to instead stay with organic felt – which they just happened to also produce. That finally changed in the 1970s when Owens Corning bought a nationwide producer of asphalt shingles and led the conversion to fiberglass-reinforced shingles. Homeowners embraced their fire rating and longer warranties and fiberglass reinforcement soon became the leading substrate for residential and commercial shingles. Today, shingles covering more than 13 billion square feet are made annually with a composite of asphalt and fiberglass mat.